I. Field of the Present Invention
The present invention relates generally to electric welding apparatus, and more particularly, to a transformer for use with a welding gun mounted at the end of a robot arm.
II. Description of the Prior Art
While electric welders are well known devices, there is continuing development in the creation and production of automated electric welders. However, it is difficult to apply the previously known welder components in automated devices such as robots for several reasons. For example, very high current must be supplied to the electrodes of a welding gun and it is typical to use a specialized transformer to supply the high currents necessary to form a weld. Conventional spot welder transformers are, therefore, inherently massive and not well adapted for mounting on a displaceable robot arm. Accordingly, the transformers are mounted remotely from the welding gun or fixture and the use of electrical conductors is necessary to electrically connect the transformer to the welding electrodes. These long lengths of conductor introduce large power losses which reduce the effect of welding power at the electrodes. Thus, it becomes necessary to build larger transformers in order to compensate for these losses and supply sufficient current to the electrodes.
A further disadvantage of these large transformers is the great amount of heat generated by these devices. Auxiliary cooling systems, such as a water cooling system, are typically necessary to dissipate the great amount of heat generated in the transformer to produce sufficient welding power at the electrodes of the welding gun. Often, cables from the transformer to the welding gun are also water cooled, adding to the cost, weight and complexity of the system. Such systems increase the weight and complexity of the welding apparatus. Thus, they inhibit the practical incorporation of a welding transformer in a robot arm.
Still another problem in incorporating an electric welder in a robotic arm is that the electrical power source for operating a robot often does not supply enough electrical power to properly provide high enough currents for welding. Accordingly, it becomes necessary to incorporate two electric power sources in such a device or, at least one large power source which increases the complexity and cost of producing such a device.